title: CD4+CD28null cells are expanded and exhibit a cytolytic profile in end-stage renal disease patients on peritoneal dialysis.
abstract: BACKGROUND
  End-stage renal failure patients, including those on peritoneal dialysis (PD), exhibit several nontraditional cardiovascular (CV) risk factors. A role of CD4(+)CD28(null) T lymphocytes in the genesis of coronary artery disease (CAD) has been proposed. We investigated this cell population and examined its phenotype in a cohort of PD patients without CV disease.
  
  
  METHODS
  The frequency of the peripheral blood CD4(+)CD28(null) T-cell compartment and cytotoxic characteristic of these cells (as assessed by perforin and granzyme B expressions) were determined in 33 PD patients without CAD and 20 healthy subjects by two- and three-color flowcytometry. High-sensitivity C-reactive protein (hs-CRP) was determined by enzyme-linked immunosorbent assay. We investigated whether there was a correlation between these cells and traditional CV risk factors.
  
  
  RESULTS
  Compared to healthy controls, CD4(+)CD28(null) T cells were significantly expanded in PD patients (10.30 ± 2.03% versus 3.55 ± 0.67%, mean ± SE, P = 0.0007). Perforin and granzyme B expressions were restricted to CD4(+)CD28(null) T cells compared to CD4(+)CD28(+) T cells (<0.0001). A greater proportion of CD4(+)CD28(null) T cells in PD patients expressed these molecules (P = 0.007 and 0.04). hs-CRP level was increased in PD patients (P < 0.0001) but did not correlate with the CD4(+)CD28(null) T-cell frequency. Increasing age correlated with the CD4(+)CD28(null) cells.
  
  
  CONCLUSIONS
  PD patients exhibit a substantially increased number of circulating CD4(+)CD28(null) T cells that show a cytolytic profile before the onset of clinically significant CAD. Their significance as a nontraditional CV risk factor needs further studies.
authors.affiliation: Department of Nephrology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Ashok Kumar
authors.initials: AK
authors.lastname: Yadav
authors.forename: Vivekanand
authors.initials: V
authors.lastname: Jha
mesh_terms: D002097:C-Reactive Protein / Q000378:metabolism; D018106:CD28 Antigens / Q000378:metabolism*; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism*; D002318:Cardiovascular Diseases / Q000209:etiology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000150:complications / Q000276:immunology*; D008215:Lymphocytes, Null; D008297:Male; D008875:Middle Aged; D010530:Peritoneal Dialysis / Q000009:adverse effects*; D011379:Prognosis; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
chemical_list: D018106:CD28 Antigens; D002097:C-Reactive Protein